The present invention relates to robots and more particularly to robot controls and energy monitoring and protection systems for such controls.
In the operation of robots, any of a variety of conditions may cause one or more of the robot joint motors to become overloaded. When an overload occurs, it is desirable for personnel safety and property protection reasons to shut down the robot. Overload may occur, for example, as a result of a robot program error, a collision of the robot arm with an obstacle, a defect in a joint motor, etc.
Conventionally, motor monitoring systems operate from temperature sensors to determine when motor overload occurs and protective action needs to be initiated. Overload, i.e. excessive energization of a joint motor or drive electronics, is presumed to exist when motor overheating exists.
While the traditional motor monitoring systems provide a first level of motor overload protection, they do operate with some shortcomings. For example, there is some time delay between the time at which an overload condition arises and the temperature sensor based system responds to alarm the overload. Further, the system functions with limited accuracy in detecting the overload threshold. Finally, there is typically no backup monitoring means in the event of failure of the sensor system for any of the joint motors.
Accordingly, it is desirable that all joint motors in a robot be provided with backup monitoring protection coordinately with the primary temperature sensor based protection and that such backup protection provide fast and accurate energy monitoring.
The incorporated-reference patent applications are directed to a completely new digital robot control which has capability for relatively higher performance and with much greater functional sophistication. As such, the new digital robot control has facilitated meeting needs in the area of joint motor overload motoring and protection, and the present invention is directed to these aspects of the new digital control.